This invention relates to a device for preventing a wheel from slipping off a spindle on which it is mounted in a freely rotatable manner, particularly but not exclusively intended for roller skates and the like.
In connection with roller skates and the like, for example, a basic requirement is that the wheels be prevented from slipping off their respective spindles, and this has been conventionally accomplished through the use of cotter pins, retainer rings, and the like arrangements effective to provide a suitable wheel retainer.
Such prior arrangements, while performing successfully as wheel retainers, have the disadvantage that they cannot be readily removed from a spindle on which they have been installed unless a specific tool in the hands of a skilled person is available. Accordingly, their use can make removal of a roller skate wheels, for instance, either for replacement or just maintenance purposes, a somewhat laborious operation, and above all, makes subsequent installation of the wheels problematic because such arrangements are liable to distort and become unusable if handled improperly.
The use of nuts threaded over a correspondingly threaded end portion of the spindle involves the availability of a suitable tool for their manipulation, and in addition, nuts may work loose in operation of the roller skates, or grow tighter on the spindles and freeze the wheels thereto, thus creating problems of a well-recognized seriousness.
To obviate such drawbacks, it has been recently proposed of using a retainer cap which is fitted over the free end of the spindle and has its sidewall surface formed with two or more longitudinal slots defining strips which can be spread elastically apart. A pair of diametrically opposed such strips are formed with respective teeth on the inside which are adapted to engage in corresponding notches provided at diametrically opposed locations on the end portion of the spindle. On fitting the retainer cap over the spindle end, engagement is achieved by a snap action. To remove such a retainer cap from the spindle, it is sufficient that the cap be moved angularly through a few degrees, such that the teeth are freed from their respective notches and made to ride on the solid spindle surface to spread the cap side strips elastically apart.
This prior retainer arrangement has the inherent advantage of being quick and practical to use both at its installation stage on the spindle and removal stage therefrom to replace a wheel, for example. However, it has the non-indifferent drawback that it cannot ensure a constant and effective retaining action for the wheel. In fact, in operation of the roller skates, by reason of the substantial physical contact between the cap and the wheel, it frequently happens that they freeze together, e.g. as a consequence of dust, mud, sand, and the like getting in between the cap and the wheel, which results in the cap being dragged around and disengaged from the spindle notches. When such disengagement occurs, the wheel is let free to slip off.
Another drawback originates from the retainer cap being liable to plastic deformation, especially at the spreadable longitudinal strips thereof, such that the strips can no longer perform their function of elastic engagement in the spindle notches.